Peel, wash and cut the potatoes into uniform small pieces. Put potatoes and garlic in a large pot with cold water to cover. Add a pinch of salt and bring to a boil. Then lower heat and cook until potatoes can be pierced easily with a fork drain, reserving about 1/2 cup of potato/garlic water.

While potatoes cook, heat olive oil, minced rosemary and chopped onion in a small skillet over low heat just until onion softens a bit. Transfer potatoes to a large mixing bowl. Pour oil and onion over drained potatoes.

Add milk to still-warm skillet – just to take chill off – then pour milk over potatoes. Using a fork, a potato masher or a rubber spatula, mash potatoes with oil and milk.

Taste potatoes and season liberally with salt and freshly ground pepper. Preheat waffle iron and finish batter by beating eggs into potatoes with a whisk or handheld mixer. Whisk together flour and baking powder and fold into potato mixture with a rubber spatula.